Ink jet printers operate by ejecting tiny drops of ink from a printhead onto a printing medium, such as paper. The printhead generally includes a nozzle plate having a plurality of nozzles through which tiny ink droplets are ejected onto the paper to collectively create an image. To deliver ink to the nozzles, the printhead includes a plurality of ink firing chambers, each fluidically connected to an associated nozzle through a bore. Within each firing chamber is a heat-generating resistor that is selectively energized to heat the ink in the chamber, which creates a bubble. As the bubble expands, some of the ink is forced through the bore out of the nozzle and onto the paper. Though specific printer configurations may vary, the printhead and nozzles are often incorporated into a printer carriage inside the printer. The printhead may be integrated into the carriage, or may be a removably detached insert. In any case, the ink is supplied to the printhead by a cartridge that is inserted into, and detachably mounted, within the printhead and carriage. The cartridge is fluidically and electrically connected to the printhead and carriage through fluidic and electrical interfaces. The reliability of the cartridge and printhead assembly, and ultimately the quality of the printed image, depends in part on the proper alignment and engagement of the fluidic and electrical interfaces. Rough operation during insertion or removal of the cartridge by a user, or play between the cartridge and the printhead or carriage, can cause communication loss (e.g., print command signal loss) or a loss in print quality due to a poor fluidic connection. To secure the alignment and positioning of the cartridge within the carriage, known cartridge designs have an incorporated datum feature that provides a point of reference for insertion of the ink cartridge. In this way, the cartridge is properly positioned and engaged within the carriage and/or printhead assembly to provide adequate fluidic and electrical interconnects.
In addition to datum features, known ink jet cartridges may include a keying feature to prevent the insertion of an incompatible ink cartridge. In some cases, ink cartridges are universal and can be used on a number of different printer families. Some ink cartridges, however, contain inks that may be chemically incompatible with other ink types. If incompatible inks come into contact with one another, they could congeal and damage the printhead and nozzle assembly.
Although ink jet cartridges may vary with respect to size and shape, they have historically been large enough in width and surface area to accommodate both datum and keying features. However, it has become increasingly important to design ink jet cartridges as narrow as possible because the overall width of the cartridge influences the width of the printer. With the onset of narrower ink cartridges there is no longer the width available for both the datum and keying features.
The embodiments described hereinafter were developed in light of these and other drawbacks associated with the implementation of incorporating both datum and keying features on narrow width ink jet cartridges.